Magnesium base alloy



Patented Nov. 12, 1940 UNITED STATES PAT-ENT- OFFlCE MAGNESIUM miss Anno 'liubert Altwlcker, Bitterfeld, and Wilhelm Rosenkranz, SandersdorLnear Bitter-fold, Germany,

assignors, by mesne assignments, to Magnesium Development Corporation, a corporation of Delaware N Dra Application October 22' 1938, Se-

win: In

rial No. 236,574. 1937 y November 22,

3 (flaims. (Cl. 75-188) This invention relates to magnesium alloys. The high percentage magnesium alloys usually employed, for plastic deformation, are known to fall into two groups. The alloys of one of these groups contain a comparatively substantial proportion of alloying components, especially aluminium (e. g. between 6 and if desired, together with zinc (between 0.5 and 1%),

and consequently have in the deformed condi- 10 tion, a considerable tensile strength (e. g. be- 1 tion, even in the warm state. The magnesium- 10 alloys of the other of the two above referred to groups contain a comparatively small proportion only of alloying components, and this latter group is almost exclusively represented by alloys in'which, in addition to magnesium, and i5 apart from the usual impurities only manganese is present in amounts up to about 2.5% and preferably about 2.0% (10c. cit., alloy AM 503). Alloys of this latter group are distinguished by high resistance to corrosion, good welding prop- !0 erties and excellent malleability in the warm,

but, owing to the absence of the known hardening components aluminium and zinc, they possess a. relatively low tensile strength (e. g. between 19 and kgs. per sq. mm.), low yield :5 point (e. g. between 14 and 17 kgs. per sq. mm.) and small elongation (e. g. between 1.5 and 5%).

As theresult of endeavours to combine the advantages of both groups of alloys, viz. high tensile strength, yield pointand elongation and resistance to corrosion, it has now been ascertained that it is possible to impart to the alloys of the second group, which contain as alloying constituents substantially only manganese in amounts up to about 2.5%, properties which meet the 5 foregoing requirementsby the addition of small amounts of cerium, or other rare earth elements, up to about 1%. Such addition improves the strength, yield point and elongation of the plastically deformed alloys of magnesium and man- 0 ganese to such an extent that the values for the constants become at least equal to those of the alloys of said first mentioned group, whilst the welding properties, resistance to corrosion, and malleability, are not rendered inferior to the 5 binary magnesium-manganese alloys. The malleability, in the cold state, is even improved by comparison with the alloys of the last named group, so that it is possible, for example to work up the new alloys in the cold into sheets, without difflculty. J

The physical properties'of the aforesaid alloys may be further improved by an addition of aluq. minium and/or zinc in a total quantity of up to about 1% without impairing other favourableproperties of the alloys. When adding zinc in other hand, result in an improvement of the capability of the alloys for plastic deformation, such as extruding, forging, and rolling, and thus enable to produce thinner sections at comparatively low temperatures of deformation. In these latter alloys the elongation is lowered but slightly, whilst particularly the yield'point, and to some extent also the tensile strength of the products, is substantially increased.

The following representative examples showthe improved physical properties of the alloys according to the invention as compared with pure magnesium or with magnesium containing corresponding quantities of either cerium or man-' ganese singly.

1. MATERIAL PRESSED INTO RODS'AT 360 C.

Mechanical properties Yield No. Tensile Elon- Alloystrength, gation, i kgs.per perb g sq. mm. cent mm.

1 Puremagnesium N 17.0 8.0 10.0 2 Pure magnesium with 1.07 Ce 19.8 23. 2 10. 7 3. Pure magnesium with 2% n 22. 0 2. 0 15. 0 4 Pure magnesium with 2% Mn,

0.4% 00 28.7. 8.4 24.8 6 Pure magnesium with 2% Mn,

0.7% Go 26. 5 11. 0 22.1 6 Pure magnesium with 2% Mn,

0.4% Ce, 0.6% Zn 31. 9 7.0 29. 3

2. MATERIAL ROLLED INTO SHEETS 1 MM. THICK AT 1, Pure magnesium with 2% Mum 19.0 5.0 8.0 8 Pure magnesium with 2% .Mn.

The term yield point used herein is intended to denote the load in kilogrammes per square, millimetre a plied to a test bar which will prothis manner, the mechanical properties are generally improved; small quantities of aluminium ranging between about 0.1 and 0.5%, on the The alloys of the present invention are especially suitable for wrought goods, e. g. sheets, extrusions and i'orgings. The maximum permissible cerium content can be regarded as 1.5%, but preferably not more than about 1% is to be used.

The cerium in the alloys according to the invention may be replaced by the so-called cerium Mischmetall, and in the appended claims the term cerium" is to be construed as also including the latter mixture of metals.

We claim:

-1. An alloy containing between about 0.1 and about 2.5% of manganese, between about 0.1 and about 1% of cerium, and between about 0.1 and about 1% of zinc, the balance being'magnesium.

2. An alloy containing between about 0.1 and about 2.5% of manganese, between about 0.1

- and about 1% of cerium, and between about 0.1

. about 0.1 and about 2.5% of manganese, characterized by improved tensile strength, yield strength, ductility, and workability in both hot and cold conditions with respect to the samealloy devoid of cerium.

-HUBERT ALTWICKER.

WILHELM ROSENKRANZ. 

